1. Field of the Invention
This invention relates to air conditioners, and in particular, relates to a monitor and alarm system for air conditioners.
2. Description of the Related Art
Air conditioners are increasingly an essential part of office buildings and residences, particularly in southern climates. Central air conditioners typically include an outdoor condensing unit including a refrigerant compressor, an indoor evaporator unit, and a manually adjustable indoor thermostat responsive to the indoor temperature for selecting and controlling the operation of the air conditioner.
Air conditioning systems use a thermally conductive coolant such as freon in a conduit. Heat exchange systems transfer heat from inside the conduit to the outside of the conduit. In an expansion valve, the high pressure, low temperature coolant is reduced in pressure, which lowers the temperature of the coolant. The coolant then is transferred into a series of coiled tubes that act as a heat exchanger with warm air from the building, thus cooling the warm air which when cooled is circulated through the structure.
The efficient functioning of air conditioners require that there be sufficient coolant in the conduit, that the coolant be cooled, that power to the system is sufficient to operate the air conditioner, that the components of the air conditioner be present and operating. Diagnosing problems when air conditioners do not function properly, or at all, generally requires a service technician, since a typical building owner or tenant is not usually trained or knowledgeable in such matters.
Thus, there is a need for an air conditioner monitor that monitors the unit to determine if refrigerant pressure is too high or too low, to determine if the fan motor has gone out, to determine if there is a leak or if someone is attempting to steal components of the air conditioner such as the copper coils, and the like. The latter problem has become increasingly common as copper has become more valuable as a commodity. There is also a need to have a monitor that functions even if the power to the monitor has been cut, such as might occur in a theft.
There are previous systems that accomplish some of these goals. For example, some air conditioners already have a thermostat with monitors, and a computer to monitor sensors, but there is no alarm.
The patent of Anderson et al. (U.S. Pat. No. 4,038,061) has a control system for protecting an air conditioner and a malfunction indicator. The control system keeps the air conditioner from being turned on in the event of low power, and has a current sensing control.
U.S. Pat. No. 7,234,313 of Bell et al. provides a monitor and superheat calculator system for air conditioners, which has a handheld monitoring device and a remote sensing unit for temperature and pressure which is placed within the return air flow of the A/C system. Additional sensors may be provided with communication between the sensors. Data from these sensors allow a technician to diagnose A/C problems.
The furnace and air conditioner failure alarm of Kennison (U.S. Pat. No. 5,444,436) provides a battery power supply to power circuits in case of A/C power failure. An environmental temperature sensor monitors the area being air conditioned and is connected to alarm circuitry which is activated when the temperature is at an unacceptable level.
It is therefore an object of this invention to monitor the low and high pressure on air conditioning units to warn the owner of problems that need repair by an air conditioning technician, thus preventing extensive damage, and to avert theft of the air conditioning unit or the coils. Thus the invention is designed to allow easier determination of whether there is a problem with an A/C unit and of what the possible problem and its cause might be, particularly if the problem is important to the function of the air conditioning system.
It is a further object of the invention to provide a monitor and alarm that includes one or more visual or audible alarms when the monitor registers problems.
Other objects and advantages will be more fully apparent from the following disclosure and appended claims.